Design considerations for large distributed electronic mail systems

Electronic mail is one of the most important means for communication and information exchange in internetworking environments. In this thesis, three methodologies for designing large mail systems are investigated, namely, mail systems with syntax-directed naming, mail systems with location-independent access, and attribute-based mail systems. Mail systems with syntax-directed naming identify users by names which are syntactically structured according to user locations. Algorithms for load balancing among mail servers, system reconfiguration, and efficient message delivery are developed and are tested using simulation. Mail systems with location-independent access allow users to access them from different locations. Procedures for keeping track of migrated users and redirecting their mail are presented. The attribute-based mail system provides maximum flexibility to users by allowing them to identify one or more mail recipients by attributes instead of only by precise names. It can also be used in mass distribution of electronic mail. An algorithm for efficient broadcasting and searching using Minimum-weight Spanning Tree (MST) is investigated. Criteria for evaluating electronic mail systems are presented. Simulation experiments are used to test the procedures and algorithms, and to study the performance of the three mail systems.